Landlocked Atlantic Salmon Salmo Salar L
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Landlocked Atlantic salmon Salmo salar L. and trout Salmo trutta L. in the regulated River Klarälven, Sweden Faculty of Social and Life Sciences Biology Conservation and management of migratory salmonids requires an understanding of their ecology at multiple scales, and a holistic view, including assessment of historical and present anthropogenic impacts. In the regulated River Klarälven, with 11 hydropower dams, populations of landlocked Atlantic salmon Salmo salar and migratory brown trout Salmo trutta have declined due to human activities. Maintaining viable populations of salmon in the River Klarälven has high priority, given Johnny R Norrgård there are fewer than 10 native stocks of landlocked salmon in Europe. To date, natural smolt production has been maintained by collecting and transporting spawners past eight hydroelectric plants in the river, where they are released to spawn. No functioning fish passage facilities are available that allow the fish to return to the lake. To evaluate the situation for landlocked salmon and migratory trout in Lake Vänern and the River Klarälven, an analysis of catch and river return data, based on data sets covering time periods from 15 to 200 years, was performed. In addition, the Landlocked Atlantic loss rates and behavior of downstream-migrating wild salmon smolts as they swam past eight power stations in the regulated River Klarälven was quantified. For the migration study, wild salmon smolts were tagged with acoustic transmitters, and the smolts salmon Salmo salar L. were monitored as they swam along a 180 km long river segment, including eight dams, with regulated and unregulated stretches. Kaplan-Meier estimations showed that only 16% of the smolts passed all eight dams. The loss due to HEP passages was estimated to be 76%, which contrasts with and trout Salmo trutta L. the 8% loss along unregulated control stretches. Migration speed was 83% lower along regulated stretches than along unregulated stretches, and migration speed at regulated stretches was dependent on fish size, with large fish moving slower than small fish. in the regulated River The analysis of historical data showed that annual returns of wild salmon are less than 3% of what they were at the beginning of the 19th century. Returns of wild trout are even lower, with just some 30 fish caught annually. Lack of basic ecological information, as river return and fisheries catch rates, Klarälven, Sweden estimates of wild smolt production and survival, and releases of hatchery-reared fish, complicate an effective management of these unique populations. There is need for coordination of present and future research, monitoring, and restoration strategies. In this thesis I identify some measures to improve the status of the River Klarälven salmon and trout that should be of broad interest to Implications for conservation and management resource and fishery managers. Karlstad University Studies ISSN 1403-8099 Karlstad University Studies ISBN 978-91-7063-389-8 2011:53 Johnny R Norrgård Landlocked Atlantic salmon Salmo salar L. and trout Salmo trutta L. in the regulated River Klarälven, Sweden Implications for conservation and management Karlstad University Studies 2011:53 Johnny R Norrgård. Landlocked Atlantic salmon Salmo salar L. and trout Salmo trutta L. in the regulated River Klarälven, Sweden - Implications for conservation and management Licentiate Thesis Karlstad University Studies 2011:53 ISSN 1403-8099 ISBN 978-91-7063-389-8 © The Author Distribution: Karlstad University Faculty of Social and Life Sciences Biology SE-651 88 Karlstad Sweden +46 54 700 10 00 www.kau.se Print: Universitetstryckeriet, Karlstad 2011 ABSTRACT Conservation and management of migratory salmonids requires an understanding of their ecology at multiple scales, and a holistic view, including assessment of historical and present anthropogenic impacts. In the regulated River Klarälven, with 11 hydropower dams, populations of landlocked Atlantic salmon Salmo salar and migratory brown trout Salmo trutta have declined due to human activities. Maintaining viable populations of salmon in the River Klarälven has high priority, given there are fewer than 10 native stocks of landlocked salmon in Europe. To date, natural smolt production has been maintained by collecting and transporting spawners past eight hydroelectric plants in the river, where they are released to spawn. No functioning fish passage facilities are available that allow the fish to return to the lake. To evaluate the situation for landlocked salmon and migratory trout in Lake Vänern and the River Klarälven, an analysis of catch and river return data, based on data sets covering time periods from 15 to 200 years, was performed. In addition, the loss rates and behavior of downstream-migrating wild salmon smolts as they swam past eight power stations in the regulated River Klarälven was quantified. For the migration study, wild salmon smolts were tagged with acoustic transmitters, and the smolts were monitored as they swam along a 180 km long river segment, including eight dams, with regulated and unregulated stretches. Kaplan-Meier estimations showed that only 16% of the smolts passed all eight dams. The loss due to HEP passages was estimated to be 76%, which contrasts with the 8% loss along unregulated control stretches. Migration speed was 83% lower along regulated stretches than along unregulated stretches, and migration speed at regulated stretches was dependent on fish size, with large fish moving slower than small fish. The analysis of historical data showed that annual returns of wild salmon are less than 3% of what they were at the beginning of the 19th century. Returns of wild trout are even lower, with just some 30 fish caught annually. Lack of basic ecological information, as river return and fisheries catch rates, estimates of wild smolt production and survival, and releases of hatchery-reared fish, complicate an effective management of these unique populations. There is need for coordination of present and future research, monitoring and restoration strategies. In this thesis I identify some measures to improve the status of the River Klarälven salmon and trout that should be of broad interest to resource and fishery managers. CONTENTS PUBLICATIONS ............................................................................................................................... 3 INTRODUCTION ............................................................................................................................ 4 Hydroelectric projects as migration barriers ............................................................................... 5 River Klarälven ................................................................................................................................ 6 OBJECTIVES ..................................................................................................................................... 8 MATERIAL AND METHODS....................................................................................................... 8 SUMMARY OF RESULTS ............................................................................................................. 11 DISCUSSION ................................................................................................................................... 15 Immediate implications ................................................................................................................ 18 ACKNOWLEDGMENTS .............................................................................................................. 20 REFERENCES ................................................................................................................................. 21 2 PUBLICATIONS The thesis is based on the two following papers, which are referred to by their Roman numerals. I. Piccolo JJ, Norrgård JR, Greenberg LA, Schmitz M, Bergman E. 2011. Conservation of endemic migratory salmonids in regulated rivers: A case study from Lake Vänern, Sweden. In press for Fish and Fisheries II. Norrgård JR, Greenberg LA, Piccolo JJ, Schmitz M, Bergman E. 2011. Multiplicative loss of landlocked salmon Salmo salar L. smolts during downstream migration through multiple dams. Submitted Paper I is reproduced with kind permission from the publisher. 3 INTRODUCTION Atlantic salmon Salmo salar L. and sea-migratory brown trout Salmo trutta L. show a complex and diverse array of life history patterns. Typically, their life starts with a freshwater phase, followed by smoltification and migration to the sea for feeding and growth, and a return to their native river for spawning (Elliott 1994; Thorstad et al 2011). After the last glacial period some Atlantic salmon and brown trout stocks were isolated from the sea in both North America and Europe. These landlocked populations complete their entire life cycle in freshwater, mainly spending their adult growth period in large lakes instead of the sea. Although both Atlantic salmon and brown trout are well studied species, relatively little is known about these landlocked lake-migrating stocks (Klemetsen et al 2003). Declines in native anadromous salmonid populations worldwide are well-documented (Mills 1991; Parrish et al 1998; Lichatowich 1999; Behnke 2002; IUCN 2011), and the landlocked stocks of salmon have also declined throughout their whole distribution range (Kazakov 1992). At present, landlocked European populations of salmonids are found in Norway, Sweden, Finland and Russian Karelia